I'm not sure if anyone has actually said but - a 6 hour ride, I presume at a decent pace, you should be sore afterwards. This is completely normal and basically there is nothing you can do about it (Yes, it's worse as we get older).
I've been following this thread with some interest, knowing that I was going to a post exercise muscle recovery seminar this morning + Prof. Ken Nosaka was out over from Perth a few weeks ago presenting mechanisms of muscle damage, probably the #1 authority in the world and very generous with his time.
The inflammation process is causing the DOMS, it will run its time course no matter what you do, taking some NSAIDs immediately following may attenuate the extent of inflammation, and therefore shorten the time course, too late know. Asprin, has no effect on sports performance and there is no decent evidence to support reducing/helping doms.
Massage and or stretching waste of time, it gives an acute relief that has no effect on performance of time course of recovery. Nothing wrong with a foam roller, they work very well, especially if the Mrs is non compliant to massage requests.
Ice baths / hot - cold, waste of time mostly, if professional footballers do it, it's usually a waste of time. The hydrostatic pressure may help recovery, along with the cold reducing inflammation, but data presented today showed people who did not do ice baths recovered faster! No convincing evidence for or against.
lactic acid returns to normal levels within the hour, creatine kinase peaks around 48 hrs (and non of the above change this), no evidence to support these affecting recovery.
If it was a short session you were getting this sore from, or unaccustomed exercise I'd be worried.
Eat a good diet - taking the protein you mention is good, replenish your fluid levels asap (driftking metion pre-post ride weighing in another post, great apporach), take some nsaids immediately following... and if you are dead serious about a fast recovery can't go past anabolic steroids, they work.
It's a shame the tour team doctors are so secretive about what they do, nothing published, I imagine because a lot of it borders on the illegal/unethical.